Bent spine syndrome as an early manifestation of myotonic dystrophy type 1.

Myotonic dystrophy type 1 (DM1) is highly variable systemic disorder with prominent myopathic involvement in distal limb, facial, and jaw muscles. Bent spine syndrome presents a diagnostic challenge, and usually, DM1 is not included in the differential. We report 2 cases of DM1 with bent spine syndrome. To further investigate this phenomenon, we compared weakness patterns in a cohort of DM1 with cohorts of amyotrophic lateral sclerosis and inclusion body myositis and found that neck extension weakness is most pronounced in DM1. Our findings emphasize the heterogeneity of DM1 and underscore the importance of considering DM1 as a cause of bent spine syndrome.